There is, as I understand it, strong support for the ideas of "Reciprocal altruism" and "kin altruism," from the evolutionary psychologists / evolutionary biologists. Game theory research[1] by Robert Axelrod[2][4] has shed some light on the nature of altruism, cooperation and competition, as has the work of Robert Trivers[3].

[1]: http://en.wikipedia.org/wiki/Tit_for_tat

[2]: http://en.wikipedia.org/wiki/Robert_Axelrod

[3]: http://en.wikipedia.org/wiki/Robert_Trivers

[4]: http://en.wikipedia.org/wiki/Evolution_of_cooperation